## Profile

Qiaochu Yuan
Worked at Machine Intelligence Research Institute
Attends University of California, Berkeley
Lives in Berkeley, CA
2,313 followers|160,578 views

## Stream

### Qiaochu Yuan

Shared publicly  -

I was staring at a bonfire on a beach the other day and realized that I didn’t understand anything about fire and how it works. (For example: what determines its color?) So I looked up some s…
6

There was a whole thing a few years ago about explaining this to 11-year olds. :-)
http://www.centerforcommunicatingscience.org/what-is-a-flame/﻿

### Qiaochu Yuan

Shared publicly  -

Ramanujan stuff.﻿
I went to see The Man Who Knew Infinity yesterday. I have nothing much to say about the movie as a movie that wasn’t already said in Scott Aaronson’s review, except that I learned a few…
13
4

The closest cinema where it's playing seems to be a 1-hour drive away, south of Los Angeles near the coast.  And I bet that's under optimistic assumptions about traffic.  So it's about time and general hassle.﻿

### Qiaochu Yuan

Shared publicly  -

Previously we suggested that if we think of commutative algebras as secretly being functions on some sort of spaces, we should correspondingly think of cocommutative coalgebras as secretly being di…
3

### Qiaochu Yuan

Shared publicly  -

Here's a fun question: is the empty function (from the empty set to itself) constant? Is it locally constant? ﻿
3
1

Presumably a constant function f:X->Y should factor through pt->Y uniquely. If that's the only definition, and X is empty, then "f is constant" iff |Y| = 1. Which is pretty weird!﻿

### Qiaochu Yuan

Shared publicly  -
6
1

### Qiaochu Yuan

Shared publicly  -

It's common to think of monads as generalized algebraic theories; the most familiar examples, such as the monads on $latex \text{Set}$ encoding groups, rings, and so forth, have this flavor. Howeve...
4
1

### Qiaochu Yuan

Shared publicly  -

4

### Qiaochu Yuan

Shared publicly  -

Mathematicians are very fond of thinking about algebras. In particular, it’s common to think of commutative algebras as consisting of functions of some sort on spaces of some sort. Less commo…
6
1

### Qiaochu Yuan

Shared publicly  -

Very nice visualization of prime factorizations. ﻿
10
4

iirc, this is included in http://incrediblenumbersapp.com/, which is a nice app for kids﻿

### Qiaochu Yuan

Shared publicly  -

Here's a dumb riddle. We all know that a meromorphic function on a Riemann surface is a function to CP^1. We also all know that meromorphic functions on a Riemann surface form a field, and in particular a ring. So... why isn't CP^1 a ring object in the category of Riemann surfaces?

(It took me an embarrassingly long time to figure this out.)﻿
1

Is it because the point is not a Riemann surface?﻿
People
Have them in circles
2,313 people
Work
Occupation
Employment
• Machine Intelligence Research Institute
Visiting Fellow, 2013 - 2013
• PROMYS
Counselor, 2012 - 2012
• Stack Overflow, Inc.
Intern, 2011 - 2011
Places
Currently
Berkeley, CA
Previously
Boston, MA - New York, NY - Bellevue, WA - Nanjing, China - Singapore - Vancouver, WA - Cambridge, UK
Story
Introduction
I'm a third-year graduate student in mathematics at UC Berkeley.
Bragging rights
USA Mathematical Olympiad Honorable Mention (2006), Siemens-Westinghouse Science and Technology Competition Semifinalist (2007), Intel Science Talent Search Finalist (2008), William Lowell Putnam Mathematical Competition Honorable Mention (2009), NSF Fellow (2012)
Education
• University of California, Berkeley
Mathematics, 2012 - present
• Massachusetts Institute of Technology
Mathematics, 2008 - 2012
• University of Cambridge
Mathematics, 2010 - 2011